Although a variety of quaternary ammonium compounds or "quats" have been used and proposed for use in personal care products, many prior art quats have drawbacks associated therewith. For example, light color and low odor are essential for obtaining customer acceptance and for achieving stable and acceptable long-term product aesthetic properties. Indeed, there is increasing interest in obtaining personal care product formulations which are translucent or transparent (that is, clear) liquids, even to the point of obtaining a crystal clear dispersion. The discovery of such clear compositions requires careful identification of proper quaternary and/or polyquaternary ammonium compounds, together with appropriate additives, such as surfactants and solvents, which act together to achieve the desired appearance. Such clear personal care products would include: hair conditioners, shampoos, skin conditioners, body washes, liquid bath soaps, facial cleansers, make-up removers, baby baths, and hand soaps.
Each of these applications presents its own complications; because the interactions between the various components of the compositions must be considered in addition to the individual chemistry of each component. For example, consider the formulation of a combined conditioner and shampoo composition, also known as conditioning shampoos, two-in-one shampoos, or two-in-ones. Two-in-ones contain ingredients that both clean and condition the hair in one application and are thus very time efficient. Two-in-ones, however, are traditionally pearlescent or opaque because most conditioning ingredients, for example, quaternary ammonium compounds, are not soluble in anionic detergent carriers in the normal formulation parameters for these products. The detergent compounds with the widest range of cleaning properties are generally anionic (negatively charged) surfactants. Such anionic surfactants, for example, may include the alkylbenzene sulfonates, .alpha.-olefin sulfonates, sodium lauryl ether sulfates, sodium lauryl sulfates, ammonium lauryl ether sulfates, and ammonium lauryl sulfates available from Witco Corporation under the WITCOLATE.RTM. and WITCONATE.RTM. trademarks. In contrast, as exemplified by the quaternary ammonium compounds discussed above, conditioners are generally cationic (positively charged). Thus, when the anionic detergent ingredients and cationic conditioning ingredients are present in the same aqueous solution, as in two-in-ones, these ingredients have a natural tendency to complex together or even precipitate out of solution. This complexation or dispersion usually results in a pearlescent or opaque mixture which may interfere with the performance of both the detergent compound and conditioning compound and is therefore undesirable.
Moreover, it has been heretofore difficult to solubilize resins, e.g. anionic resins, in such prior art hair care formulations. Such resins typically require heat to ring open and reveal the anionic charge. Furthermore, it is extremely difficult to formulate these types of resins with cationic surfactants at all, let alone obtain clear formulations using these resins.
UK Patent No. 2 160 421 relates to a conditioning and softening composition that includes certain quaternary ammonium compounds. All of the examples prepared by this reference include coconut diethanolamide; a well-known thickening agent or viscosity-enhancing agent. The instant invention does not require diethanolamide or other conventional thickening agents or viscosity control agents, since the instant invention provides a clear formulation with a high viscosity from the components specified.
EP 0 511 652 A1 relates to a hair shampoo-conditioner formulation including an anionic cleansing surfactant, a polymeric cationic conditioning compound, a cationic conditioning surfactant, a fatty ester, and water. In contrast to the formulations of the instant invention, which are clear and have high viscosities, the compositions of EP 0 511 652 A1 are all opaque to pearlescent formulations (Examples 1 and 3-10), often with low viscosities. In addition, the compositions of EP 0 511 652 A1 require a polymeric cationic conditioning compound, such as quarternized guar gum, which is a conventional thickening agent that is not a required aspect of the instant invention, and is preferably excluded from the instant invention.
WO 97/12020 relates to a liquid laundry detergent formulation comprising an anionic surfactant component and a quaternary ammonium compound component. The compositions of WO 97/12020 are not said to be clear or exhibit high viscosity and, as set forth in more detail below, formulations made according to the teachings of the Examples of WO 97/12020 are not clear.
In some prior art formulations, lanolin, wheat germ and other natural broad-based chain distribution oils are used as the quaternary ammonium compound. The use of such quaternaries is not advantageous since the same do not build-up viscosity; therefore those quaternaries cannot achieve the benefits of the present invention.